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Re: Wireless transmission of power,

Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>

At 10:55 AM 3/17/2005, you wrote:
Original poster: "Sean Taylor" <sstaylor@xxxxxxxx>

To start with, power stations are the most inefficient part. The Second
Law of thermodynamics limits the efficiency of a practical heat engine to
about 40%.

I'm getting kinda tired of this whole discussion, but I had to jump in on this part. Where do you think the energy for the central "transmitter" would come from? It would have to be a power plant, and a HUGE one at that. The total power consumption of the world in 2002 was over 15 TRILLION KWHrs. If the load was steady year round, this translates to a power of about 1.7 GW, not to mention demand loads, etc.

Uhhh... 1.7 GW isn't all that big a power plant. 2 GW is a standard power plant size.

I think you missed a factor of a thousand.. 15 Trillion (15E12) kWh is 15E15 Wh, divided by 8766 hrs/yr is 1.7 TW... 1700 GW, a substantially larger power plant.

However, consider that sunlight falling on the earth's surface is 1kW/m2. Figure you get 1/3 that on the average (8hr/dy sunlight) and you get 30% conversion efficiency to electricity using solar thermal electric. Call it 100 W/m2 to your transmitter. So, you need about 17 billion square meters of collector, which sounds like a lot, at first. But, it's 17,000 square kilometers, or a square about 130 km on a side. There are several places in California, Nevada, Arizona, etc. (or northern Mexico) which could accomodate such a facility without too much trouble.

But the real question, since there will be inevitable inefficiencies in transmitting and receiving the power by the Tesla approach (he never claimed it was lossless, I think), why not just put the solar electric collectors near the loads and use conventional distribution technology for the "last mile".

FWIW, I think 15 PWh might be an underestimate.

 Good luck
building a plant that large, and making a coil from wire that will handle
that kind of power!  We're also ignoring the inefficiency of the Earth and
its atmosphere as conductors, as well as the problem of making the upper
atmosphese conductive - satellite communication would no longer work!
It's time to face reality: The idea of wireless transmission of power for
the world would just not work out.

Sean Taylor, MSEE
Urbana, IL